2 degrees Celsius

The average global temperature has already increased by more than 1 degree Celsius over pre-industrial levels, according to a just-released United Nations-backed study on the world’s oceans, leading to warming oceans and causing sea level rise. If we hit 2 degrees C (or 3.6 degrees Fahrenheit) the implications could be catastrophic, especially for low-lying and coastal areas.

For instance, if temperatures increase above that threshold, the Arctic Ocean would be ice-free in September — when ice cover is at its lowest — as many as one out of every three years; if we manage to cap the temperature increase at 1.5 degrees C, it’d happen only one out of every 100 years.


Sea levels rose about 15 centimeters worldwide during the 20th century, researchers said; if temperatures rise above the 2-degree C threshold, they could rise more than 3 feet by the end of the century, leading to intensified flooding and storm surges.

The report has more than 100 authors from 36 countries, and references about 7,000 scientific publications.

Sean Smyth can be reached at sean.smyth@globe.com. Follow him on Twitter @smythsays.